With the development of computer systems in general, and with the development of personal computers and workstations in particular, various devices for controlling the position and movement of a cursor on the two-dimensional display provided by a computer display unit have been developed. Typical of such devices are the "mouse" device, the joystick device, and the like.
Recently, systems for displaying a three-dimensional stereoscopic image of an object on a display unit have been developed. Such systems provide for the display of a cursor which, when viewed as a part of the three-dimensional stereoscopic display (by the use of special glasses, for example), identify a point in three-dimensional space.
However, no device (or, at least, no easily usable device) has been developed for operator manipulation of the cursor in such a three-dimensional stereoscopic display. Thus, there is a need for a three-dimensional cursor control device which permits the operator to conveniently and accurately control the movement and position of the cursor in three-dimensional space.
Such a three-dimensional cursor control device should be "user friendly". That is to say, there should be positional congruency between manipulation of the device by the user and the positioning of the cursor in three-dimensional space. In addition, there should be movement congruency between manipulation of the device by the user and movement of the cursor in three-dimensional space.
The following patents are considered to be typical of the prior art relative to the invention disclosed herein: U.S. Pat. Nos. 3,613,501; 4,214,267; 4,607,255; 4,685,070; 4,766,423; 4,791,478; 4,812,829; 4,823,170; 4,835,528; 4,839,838; and 4,840,567.